(1) Field of the Invention
The invention relates to the technical field of weatherproof surrounds or tight sealing frames, for removable emergency panels, for walls of vehicles.
(2) Description of Related Art
The invention is useful to various types of vehicle, even if it originates in the aviation industry. For example, the invention may be applied to rotary-wing aircraft.
In non-limiting manner, the invention may be applied to a helicopter in which, for example, the wall is part of a fuselage. The invention may also be applied to high-speed and long-range helicopters of the “hybrid” type, e.g. such as described in Documents FR 2 916 418, FR 2 916 419, or FR 2 916 420.
In another example, the rotary-wing aircraft is a drone that is unmanned, being flown from a remote pilot station, and the removable panel can then typically close off an emergency hatchway giving access into its fuselage. In the embodiments for aircrafts, the wall or fuselage may be as described by Document FR 2 896 768.
Consequently, the term “removable panel” of a wall is used herein to designate various types of structure, in particular in the form of windows or of wall elements of the vehicle. Such a removable panel may thus be at least partially opaque and/or at least partially translucent, or genuinely transparent.
The term “jettisonable panels” is used if such a panel is said to be “removable” or ejected in an “emergency” or “escape” situation, so that, so long as the vehicle is in the normal operating state, said panel is fastened rigidly (i.e. held securely) in the wall. It can then be considered to be an “integrated” element of the fuselage or to be trim therefor.
Conversely, in an emergency, the removable emergency panel can be disunited and separated from the remainder of the wall of the vehicle, so as to open up access to the inside of the vehicle and/or to the outside thereof.
It can therefore be understood that a “weatherproof surround” for such a removable emergency panel is a structure that connects said removable panel to the wall that surrounds it, when the vehicle is in its normal operating state. In such a state, the panel is connected via the weatherproof surround to the wall of the vehicle, sufficiently rigidly and hermetically to satisfy the conditions under which the vehicle is operated.
If the panel is removable in the event of an emergency, such weatherproof surrounds (optionally together with their holding and detaching structures) may be referred to as “jettison seals”. Other commonly used weatherproof surrounds that may be referred to as “seals with unlocking key and strip” or “handled seals” are mentioned below.
The technical problem lying behind the invention is described below.
Firstly, it is desirable for the safety performance of existing jettison seals to be improved significantly, in particular as regards ease of jettisoning (i.e. ejecting).
This involves improving prevention of any unacceptable malfunctioning that might be encountered with existing jettison seals, and also keeping up with the increased technical constraints to which modern aircraft are subjected.
For example, for high-speed and long-range “hybrid” helicopters, the following constraints are being made more stringent:
strength of the materials (both static and dynamic strength);
dimensional constraints, with windows having larger areas;
in a normal operating state, staying in place even with removable panels that are heavier (e.g. luxury or “VIP” windows having insulating multiple glazing);
resistance (e.g. to pressure) at high speeds;
temperature, e.g. at high speeds and at high flight altitudes; and
on-board weight, with “weight-paring” being draconian on modern aircraft.
It is worth briefly recalling the applicable regulations relating to safety performance of existing jettison seals designed for rotary-wing aircraft. Currently, those regulations are defined by the Nov. 14, 2003 Final Decision EC2003/16/RM by the European Aviation Safety Agency on certification specifications for large rotorcraft. That Decision is often referred to as “CS-29”.
In that Final Decision EC2003/16/RM, paragraph CS-29.809 concerns emergency exit arrangement.
In particular, that Decision provides as follows in its paragraphs:
(a) each emergency exit must consist of a movable door or hatch in the external walls of the fuselage and must provide an unobstructed opening to the outside;
(b) each emergency exit must be openable from the inside and from the outside;
(c) the means of opening each emergency exit must be simple and obvious and may not require exceptional effort;
(d) there must be means for locking each emergency exit and for preventing opening in flight inadvertently or as a result of mechanical failure;
(e) there must be means to minimize the possibility of any emergency exit jamming in a minor crash landing as a result of fuselage deformation under ultimate inertial forces (see CS-29.783).
In addition, paragraph AC 29-2C §29.809 of that Decision provides, in particular, as follows:
For the procedures, the effort required to open the emergency exit, as evaluated by conducting the tests (tests as defined in §29.8070 must lie within the range 40 pounds (18.14 kilograms (kg) to 50 pounds (22.68 kg), and it is recommended that a person of slight stature, such as a female in range 90 pounds to 100 pounds, be used for the exit opening tests and demonstrations. In any case, the average load required to operate the exit release mechanism and open the exit should not exceed 50 pounds (22.68 kg), and the maximum individual load of a test series should not exceed 55 pounds (24.95 kg).
In addition, paragraph AC 29 §29.803(d) of that Decision provides, in particular, that with rotary-wing aircraft having emergency exits, it must be possible for the maximum seating capacity (including both passengers and crew members as required by flight regulations) to be evacuated from the aircraft to the ground within 90 seconds.
Although generally satisfactory, current jettison weatherproof surrounds would benefit from improvements regarding two points mentioned below. Also, such surrounds might complicate certification, or indeed compromise the safety desired for future aircraft that have flight characteristics and/or wall structures that are more constraining than currently.
If the weatherproof surround is a jettison seal with a unlocking strip or “handled seal”, changes in the structural characteristics of the removable emergency panel (in its weight, in its dimensions, in its physical properties, etc.) can have direct consequences on the opening operation and thus on evacuation (within a maximum time of 90 seconds) as defined by the currently applicable regulations.
Evacuation should be operational over the entire range of temperatures to which the aircraft might be exposed when in service.
In this context, it would be desirable for jettison weatherproof surrounds to be certified as emergency exits without having to make provision for some other heavier wall structure to be jettisoned, typically when the removable panel is a window and the wall structure that holds it in the fuselage is a door. For example, when the panel is a door window, it is problematic that it is not possible for the window to be certified as an emergency exit, and that the entire door in which the window is installed must be certified.
In practice, the technological background of the invention does not make it possible to achieve these objects.
In addition to above-mentioned Documents FR 2 896 768, FR 2 916 418, FR 2 916 419, or FR 2 916 420, and Final Decision EC2003/16/RM of Nov. 14, 2003, mention may be made of other documents from the state of the art.
Other documents relating to panel surrounds are discussed below.
Document FR 1 390 412 describes opening panels of a vehicle. That document proposes increasing the deformability of a seal, but the angles that it is possible to achieve (FIG. 6) are limited.
Document FR 2 205 622 describes a seal for surrounding a window pane with elongate beads, a slot, and a fastener hinge. That document proposes increasing the deformability of a seal, but the angles that it is possible to achieve (FIG. 2) are limited.
Document DE 171 519 describes a window surround making jettisoning possible, with, on the inside face, means having a handle for cutting the surround.
Document DE 22 33 525 describes a seal for surrounding a window with an outside slot in which a fastener hinge is received. That document proposes a seal having a deformation angle that is limited in amplitude, with such deformation being possible on only one face of the seal.
Document DE 916 501 describes a single seal provided with a first extreme zone and with a second extreme zone that are connected together via an intermediate zone. That single seal does not appear to be applicable to an aircraft, in particular due to aerodynamic stresses.
Document DE 202 17 925 describes an emergency ejection window for a railcar or for a bus. That document does not describe any means making it possible, as required in the field of aviation, to combine holding the window pane in place under in-flight aerodynamic forces while also enabling the window to be ejected under maximum loads. That document describes a complex handle-and-linkage device to be pulled in order to eject the window pane.
Document EP 0 249 560 describes a channel-section member that fits over the edge of a window pane and that co-operates with a closure section member.
Document EP 0 175 981 describes a gasket, for fastening a window against the border of an opening in a motor vehicle. That gasket is provided with a reception slot for receiving a window pane, and with an adapter element for fastening to the border of the opening in the motor vehicle. Together, the gasket and the adapter element constitute a securing seal. That document does not describe a removable emergency panel for an aircraft, or how to enable such a removable panel to withstand in-flight thermal expansion, or how to procure stiffness guaranteeing that such a panel is held in position in spite of the aerodynamic forces to which it is subjected in flight, while also remaining weatherproof. In addition, the large windows of an aircraft must be jettisonable in order to allow passengers to evacuate in the event of incidents. This function is not described by Document EP 0 175 981. That document thus does not describe jettisoning large-size windows that would open up openings in the fuselage of the aircraft, such openings being particularly useful if the conventional accesses of the aircraft are blocked.
Document EP 0 748 710 describes a device for unfastening a window pane in an emergency, for a rail vehicle. A window pane is held in position via a peripheral cord that must be cut in order to release the window pane to be unfastened and in order to evacuate the occupants. That unfastening device is heavy and complex, and comprises numerous assembled components. In addition, that unfastening device requires the seal or the cord to be destroyed in order to unfasten the window pane.
Document FR 2 858 950 relates to a sealing module for sealing a window pane that is fixed and that is therefore, a priori, not suitable for being removed.
Document FR 2 548 256 describes two elements, namely a molding and a glazing bead that co-operate to form two slots. Two lips of the molding define one slot while a lip of said molding co-operates with a lip of the glazing bead to form the second slot.
Document FR 2 766 156 describes a window pane surround making it possible to jettison a window. Pullable cutting means are provided on at least a portion of the perimeter of the window pane for the purpose of cutting the surround into a plurality of portions, thereby disuniting the window pane from the support. That seal is dedicated exclusively to a single given model (geometrical shape and size) of window. Each model of window requires a specific seal to be manufactured, thereby giving rise to relatively high costs. Once the core of the seal has been cut, the surround cannot be reused. In order to accommodate differential expansion of the carrier structure and of the window, it would be necessary to make the seal excessively big, to the detriment of its weight and of its visual appearance.
Document FR 2 935 347 describes a weatherproof surround for a large window of a rotary-wing aircraft. That surround includes a first weatherproofing seal and a second weatherproofing seal, removable holding means, with two rigid outer webs that clamp the seals and the window onto the carrier structure in the mounted state.